Method for controlling an induction cooking hob with a plurality of induction coils and an induction cooking hob

Abstract

A method for controlling a cooking hob with one or more induction coils covered by a cookware and forming a cooking zone. All induction coils of the cooking zone are alternately activated. The method includes setting an average power to be transferred to the cookware by a user, determining a frequency, estimating a maximum average power if all induction coils of the cooking zone would be activated with said frequency, estimating a percentage power defined as quotient between the set average power and the estimated maximum average power, estimating a calculated number of coils defined as product of the number of coils within the cooking zone and the percentage power, defining a minimum number of simultaneously activated coils within the cooking zone by an integer value of the calculated number, and defining a temporal activation of a further one of the coils by a fractional part of the calculated number.

The invention claimed is: 
     
       1. A method for controlling an induction cooking hob with a plurality of induction coils, wherein groups of induction coils are each configured to be covered by a respective piece of cookware to form a plurality of cooking zones, each having a set power and a set frequency, the method comprising the steps of:
 setting, by a user, an average power (P) to be transferred to the piece of cookware on each of the plurality of cooking zones, 
 determining a same frequency for the induction coils forming each of the plurality of cooking zones based on the set frequency of the cooking zone with a highest set power, 
 estimating a maximum average power (PM) that occurs when all of the induction coils forming each of the plurality of cooking zones are activated with the determined same frequency, 
 estimating a percentage power (PP) defined as quotient between the set average power (P) and the estimated maximum average power (PM), 
 estimating a calculated number (CN) of induction coils defined as a product of a number (N) of the induction coils within each of the plurality of cooking zones and the percentage power (PP), 
 alternately activating a minimum of the induction coils forming each of the plurality of cooking zones at the same determined frequency to heat each of the plurality of cooking zones, and 
 wherein the minimum number of simultaneously activated induction coils within each of the plurality of cooking zones is defined by an integer value of the calculated number (CN),and 
 wherein a temporal activation of a further one of the induction coils is defined by a fractional part of the calculated number (CN). 
 
     
     
       2. The method according to  claim 1 ,
 characterized in that 
 the induction coils of each of the plurality of the cooking zones are activated and deactivated according to a time schedule including a plurality of subsequent cycles, wherein each cycle corresponds with a combination of activated induction coils. 
 
     
     
       3. The method according to  claim 2 ,
 characterized in that 
 during each cycle at least the minimum number of simultaneously activated induction coils is activated. 
 
     
     
       4. The method according to  claim 2 ,
 characterized in that 
 during each cycle at most the minimum number of simultaneously activated induction coils and the further one of the induction coils is activated. 
 
     
     
       5. The method according to  claim 2 , characterized in that the number of cycles with the further one of the induction coils and the number of cycles without the further one of the induction coils corresponds with the fractional part of the calculated number (CN). 
     
     
       6. The method according to  claim 2 , characterized in that the time of a cycle following another cycle with the same number of activated induction coils is between 0.3 s and 0.6 s. 
     
     
       7. The method according to  claim 2 , characterized in that the time of a cycle following another cycle with a different number of activated induction coils is between 1.2 s and 1.8 s. 
     
     
       8. The method according to  claim 2 ,
 characterized in that 
 in subsequent cycles with the same number of activated induction coils the activated induction coils are cyclically interchanged. 
 
     
     
       9. The method according to  claim 1 , further comprising the step of adjusting the average power (P) by activating and deactivating of some the induction coils while maintaining the same frequency. 
     
     
       10. The method according to  claim 9 , wherein variation of the frequency is not used to vary the average power (P). 
     
     
       11. The method according to  claim 1 , wherein all of the activated induction coils operate at the same frequency. 
     
     
       12. An induction cooking hob ( 10 ) comprising:
 a plurality of induction coils ( 20 ), wherein groups of induction coils ( 22 ,  24 ,  26 ,  28 ) are configured to be covered by a piece of cookware ( 16 ) and form a plurality of cooking zones, each having a set power and a set frequency; 
 a user interface used by a user to set an average power (P) to be transferred to the piece of cookware ( 16 ) on each of the plurality of cooking zones; 
 a controller electrically connected to the user interface and configured to: 
 determine a same frequency for the induction coils forming each of the plurality of cooking zones based on the set frequency of the cooking zone with a highest set power, 
 estimate a maximum average power (PM) that occurs when all of the induction coils ( 22 ,  24 ,  26 ,  28 ) forming each of the plurality of cooking zones are activated with the same determined frequency, 
 estimate a percentage power (PP) defined as quotient between the set average power (P) and the estimated maximum average power (PM), and 
 estimate a calculated number (CN) of induction coils ( 22 ,  24 ,  26 ,  28 ) defined as a product of the number (N) of induction coils ( 22 ,  24 ,  26 ,  28 ) within each of the plurality of cooking zones and the percentage power (PP), and 
 alternately activate a number of the induction coils ( 22 ,  24 ,  26 ,  28 ) forming each of the plurality of cooking zones at the same determined frequency to heat each of the plurality of cooking zones, wherein: 
 a minimum number of simultaneously activated induction coils ( 22 ,  24 ,  26 ,  28 ) within each of the plurality of cooking zones is defined by an integer value of the calculated number (CN), and 
 a temporal activation of a further one of the induction coils ( 22 ,  24 ,  26 ,  28 ) is defined by a fractional part of the calculated number (CN). 
 
     
     
       13. The induction cooking hob according to  claim 12 ,
 characterized in that 
 the induction coils ( 22 ,  24 ,  26 ,  28 ) are arranged as a matrix on a cooking surface ( 12 ) of the induction cooking hob ( 10 ). 
 
     
     
       14. The induction cooking hob according to  claim 12 ,
 characterized in that 
 the induction coils ( 22 ,  24 ,  26 ,  28 ) on the cooking surface ( 12 ) of the induction cooking hob ( 10 ) have the same sizes.